1. Field of the Invention
The present invention relates to vibrational processing apparatus and methods including apparatus and methods for plating small electronic components such as laminated chip capacitors and including barrel-polishing apparatus for applying vibration to an object to be processed to perform processes such as plating and polishing thereon. More particularly, the present invention relates to a vibrational processing apparatus and method capable of controlling the state of vibration to optimize vibration applied to an object to be processed.
2. Description of the Related Art
FIG. 9 shows a structure of a plating apparatus as an example of conventional vibrational processing apparatus. For example, a plating apparatus as illustrated is disclosed in Japanese unexamined patent publication (KOKAI) No. H5-70999. This plating apparatus 1 includes a vibration generating portion 2, a vibration transfer member 7 for transferring vibrational energy generated by the vibration generation portion 2, and a basket 8 connected to the vibration transfer member 7 for containing an object to be plated such as a chip type electronic component. The basket 8 constitutes a negative electrode. A plating process is performed with the basket 8 immersed in a plating solution in a plating solution bath 9.
The vibrational generating portion 2 includes a motor 3. An eccentric load 4 is added to the rotating shaft of the motor 3. The motor 3 is mounted on a supporting frame 5 which is elastically supported on the bottom of a case through springs 6. With such a structure, rotation of the motor 3 causes periodic fluctuations of the balance between an eccentric force produced by the eccentric load 4 and an elastic supporting force provided by the springs 6, thereby causing a swinging motion of the supporting frame 5 as a whole. Then, vibrational energy is transferred to the basket 8 through the vibration transfer member 7 connected to the supporting frame 5 to cause the basket 8 to vibrate in the plating solution periodically. As a result, objects to be plated and steel balls or media placed in the basket 8 are agitated and mixed by the vibration of the basket 8. This allows the objects to be plated to be agitated in appropriate contact with the basket 8 and therefore allows formation of uniform plating films on the surface of the objects to be plated.
The rotational speed of the motor 3 of the conventional plating apparatus is set at a fixed value. Therefore, the vibrational energy which can be generated by the vibration generating portion 2 is fixed. However, the characteristic frequencies of vibrating portions including the basket 8 vary depending on the amount, size and weight of the objects to be plated and steel balls or media charged in the basket 8. This results in a change in the degree of the agitation of the objects to be plated in the basket 8. Therefore, even if the rotational speed of the motor 3 is preset so as to apply optimum vibration to the objects to be plated, it has been necessary to reset conditions such as the rotational speed of the motor 3 by detecting optimum vibrating conditions using detecting equipment or the like each time conditions of the objects to be plated or the like contained in the basket 8 are changed. Such an operation has required much time and labor, reducing the efficiency of a plating process. Further, there has been a problem in that the thickness of plating on an object to be plated can vary because of insufficient agitation of the object if the resetting of the rotating condition of the motor 3 and the like is not carried out.
Further, the problems as described above have occurred in conventional barrel polishing apparatus. Specifically, when polishing is performed by applying vibration to an object to be polished and an abradant or medium placed in the barrel pot, the state of vibration of the barrel pot varies if the size, weight, and quality of the object to be polished vary depending on the process. This has resulted in a problem in that much time and labor is required for resetting the optimum vibrating conditions.
It is an object of the present invention to provide a vibrational processing apparatus capable of applying the optimum vibrating conditions to an object to be processed even if processing conditions such as the size and quantity of the object to be processed are changed.